Lung is an important respiratory organ of the human body and is the main place for gas exchange. Normal lung function is the guarantee for life. Therefore, lung disease is one of the common diseases that threaten human life and health, including pneumonia, bronchitis, lung cancer, pulmonary tuberculosis, emphysema and so on. Since most lung diseases require long-term drug treatment, it is especially important to increase the safety and effectiveness of the drugs and reduce the toxicity and side effects.
The lung-targeting drug delivery system can specifically concentrate the drug in the lung, increase the concentration of the drug in the lung or increase the retention time of the drug in the lung, thereby improving the efficacy of the drug and reducing the systemic toxicity and side effects. Therefore, the study of lung-targeting drug delivery system is significantly important for the treatment of lung diseases.
At present, the lung-targeting drug delivery system under research is mainly particles drug delivery system, such as microspheres, microcapsules, liposomes, nanoparticles, etc. After the particles are intravenously injected into the body, the drug-containing particles arrive at the lung through blood circulation, they may be engulfed by the reticuloendothelial system of the lung tissue or mechanically ingested by the lung capillaries, so that the drug can be concentrated in the lung tissue. However, there are some problems to be solved in the particles drug delivery system. For example, the problem of drug burst, the particle diameter and the particle size are hard to be strictly controlled, the drug loading is low, the stability is not good, the preparation process is complicated, and it is difficult to be produced in large-scale. In addition, other lung-targeting carriers include peptides, proteins, vitamins, polysaccharides, monoclonal antibodies, etc., but most of these carriers are macromolecular substances, and the drug-carrier conjugate structure after preparation is unclear, the quality is difficult to be put under strictly control, and it is difficult to be developed into new drugs.
Thus, it is necessary to develop a small molecular lung-targeting drug that has clear curative effect, safe and reliable, and the quality of which is easy to be controlled.